Alkali metals, such as sodium and potassium, can promote a tar cracking reac­tion. Catalysts, such as potassium carbonate and sodium carbonate, are effective in methane production and are available in most biomass ashes. Potassium, however, is well-known for agglomeration in fluidized beds. Studies on the effects of inorganic salts (MgC12, NaC1, FeSO4, and ZnC12) on the pyrolysis of cellulose have shown that MgCl2 does not change the overall pyrolysis but has some slight effects on gas production. For the other tested catalysts (NaC1, FeSO4, and ZnC12), an increase in char production was reported [49].